【作者】 陈会东；

【导师】 蒋建清； 于金；

【作者基本信息】 东南大学 ， 材料学， 2006， 硕士

【摘要】 江苏天工集团是全国最大的高速钢和钻头生产基地,但其生产的钻头存在着寿命低,寿命分散性较大等问题。通过对江苏天工集团生产钻头的微观组织和几何尺寸进行对比和统计分析,发现高速钢微观组织和钻头的几何尺寸是高速钢钻头寿命的主要影响因素。采用金相显微镜、扫描电镜来观察微观组织,采用拉伸试验和硬度测试来评定力学性能,研究了添加稀土、热处理工艺对M2、M42高速钢的微观组织和力学性能的影响,通过数理统计方法来分析钻头几何尺寸对寿命的影响。研究了稀土处理对高速钢微观组织的影响,结果表明,稀土处理可以提高钢的纯净度,使M2中O、S含量分别降低33%和43%;使M42中O、S含量分别降低27%。添加0.2%稀土可以改善钢的铸态组织,使M2高速钢中铸态组织中的莱氏体由原来的闭合、连续网状变为断开、不连续的半网状,莱氏体中的碳化物也由原来的棒条状变为鱼骨状;使M42钢中莱氏体网变得更薄,碳化物排列更加疏松。添加0.2%稀土可以使M2和M42锻打和轧制组织中的碳化物分布均匀,颗粒更加细小,使奥氏体晶粒更加细小均匀。添加0.2%的稀土可以使M2盘条面缩率从15.4%提高到18.8%,使M42盘条面缩率从9.1%提高到16.4%。研究了热处理工艺(退火加热温度、退火保温时间、C曲线保温时间、爆水工艺和淬火温度)对高速钢组织和力学性能的影响。结果表明,M2较好的热处理工艺为880℃保温2小时,炉冷至760℃保温5小时,爆水;淬火温度为1200℃。M42较好的热处理工艺为890℃保温3小时,炉冷至700℃保温6小时,炉冷;淬火温度为1190℃。对大量钻头的几何尺寸和寿命数据进行了统计分析,并建立了相关模型。计算结果表明,对φ5mm的钻头,当钻芯厚度控制在0.84mm~0.97mm之间、钻芯增量控制在0.8~1.9(mm/100mm)之间和直径倒锥度控制3.0~5.6(mm/100mm)之间时,钻头寿命较好。经检验,寿命试验中长寿命钻头所占比例由56%提高到79%。试验表明,经过稀土处理,采用优化后的热处理工艺,并严格控制钻芯厚度、钻芯增量和直径倒锥度,钻头的寿命和可靠性均有显著的提高。更多还原

【Abstract】 Jiang Su TianGong Co.Ltd is the largest production base of high-speed steel(HSS) and twist drills. The HSS drills produced by Jiang Su TianGong Co.Ltd have low longevity and reliability. By analysis comparison of microstructure and geometrical dimension of the drill ,It found that the effect of drills life was microstructure and drill’s geometrical dimension . With the help of optical microscope and SEM, the microstructure. was studied. Tensile test and hardness-testing was used to appraisal the mechanical property. Rare-earth treatment and heat treating technology’s was studied. By using mathematical statistics,geometrical dimension’s effect to the drill life was studied.Rare-earth treatment’s effect to the high-speed steel was studied. The experiment result showed that rare-earth can purify high speed steel. It reduced [O] content 33% in M2 and 27% in M42. It reduced [S] 43% in M2 and 27% in M42. Addition 0.2% rare-earth can improve the cast structure. It made the closed and continuous reticular eutectic carbide in M2 steel change into semi-enclosed and discontinuous reticular. It made the rods carbide in ledeburite change into fishbone carbide. It also made the ledeburite reticular more thin and loose. It can make the carbide in morphology after striking and rolling smaller and more dispersion and make the grain smaller than usual. Addition 0.2% rare-earth improved contraction of cross sectional area of M2 hot-finished rod from 15.4% to 18.8. It improved contraction of cross sectional area of M42 hot-finished rod from 9.1% to 16.4%.Heat treatment’s(including heating-up temperature,holding time,C-curve holding time,fast cooling technology,quenching temperature) effect to the high-speed steel was studied. The results showed that the optimum parameters of M2 are as follows, at 880℃for 2h and cooling in furnace, at 760℃for 5h, then quenching in water,quenching at 1200℃. The optimum parameters of M42 ware as follows, at 890℃for 3h and cooling in furnace,at 700℃for 6h and cooling in furnace. the optimum parameters of M42 is that at 890℃for 3h and cooling in furnace,at 700℃for 5h,then cooling in furnace,quenching at 1190℃.The mathematical statistics result of the drill geometrical dimension and drill life showed that the drill heart thickness、drill heart taper、diametral taper have grate effect to drill life,so they should be strictly controlled. From the mathematical statistics model,if drill’s diameter was 5mm,the heart thickness between 0.84~0.97mm,the heart taper between 0.8~1.9(mm/100mm),the diametral taper between 0.3~5.6(mm/100mm),the drills would have longer life . the experiment showed that the long life drill’s percentage can be improved from 56% to 79%.Experiment result showed rare-earth treatment,optimization heat treatment technology and pertinent更多还原